1. Field of the Invention
The invention relates to a sheet processing apparatus for aligning sheets in the direction which crosses a sheet conveying direction of the sheets and an image forming apparatus having such a sheet processing apparatus. More particularly, the invention relates to a sheet processing apparatus in which even if there are a plurality of conveying paths to which sheets are fed, it can cope with the sheets in a short processing time and relates to an image forming apparatus having such a sheet processing apparatus.
2. Description of the Related Art
In recent years, among image forming apparatuses such as printer, copying apparatus, facsimile apparatus, their multi-function apparatus, and the like for forming images onto sheets, there is an image forming apparatus having a sheet processing apparatus for ejecting the sheets in a form of a bundle. As such a sheet processing apparatus, for example, there is a sheet sorting apparatus as disclosed in Japanese Patent Application Laid-Open No. S61-33459.
According to such a sheet sorting apparatus, when the sheets are ejected, they are alternately sorted and stacked in a form of a bundle (offset-stacking), thereby enabling the sheet bundles to be clearly distinguished. FIG. 15A and FIG. 15B are schematic diagrams of the sheet sorting apparatus disclosed in Japanese Patent Application Laid-Open No. S61-33459.
According to a sheet sorting apparatus 1, sheets conveyed by fixing rollers 5 and fixing discharge rollers 6 are ejected by an upper roller 8 and a lower roller 7 serving as a pair of discharge rollers. After a rear edge of the sheet passed through the fixing discharge rollers 6, the upper roller 8 and the lower roller 7 are moved by a distance L in the direction which crosses a sheet ejecting direction by a plunger magnet 11, thereby ejecting the sheet to a discharge tray 9. The distance L is a distance between the sheet bundles which were alternately sorted.
A sheet sorting apparatus in which the ejected sheets are aligned by an aligning member for aligning the sheets and, at the same time, the sheets are shifted in the direction which crosses the sheet ejecting direction and ejected has also been developed.
However, according to the conventional sheet sorting apparatuses, since there is only one conveying path to which the sheets are fed, the sheets which are fed from a plurality of conveying paths cannot be ejected. Therefore, the conventional sheet sorting apparatus has such a problem that it is impossible to cope with the sheets which are fed from a plurality of positions.
In the sheet sorting apparatus for sorting the sheets by the aligning member for aligning the sheets, since the aligning member is moved in the direction which crosses the sheet ejecting direction, it takes a time.
Further, there is a case where the sheets which are fed are conveyed in the state where the position has been selected in a width direction of the sheet. However, since the position of the aligning member cannot be shunted in accordance with the selected ejecting position of the conveyed sheet, the aligning member is on standby at a position where the aligning member can align the sheets at any place. Consequently, there is a wasteful motion in the aligning member and it takes a time to align.